1. Field of the Invention
The present invention generally relates to high speed data communication via the AC power line and, more particularly, to providing access to a high speed data communications network on the AC power line through a standard light bulb socket or receptacle.
2. Background and Description of the Prior Art
The development of the technology for high speed or broadband data communication on the AC power line has advanced to the point where it is readily available for use in and with consumer products that can be installed and used without having to install wiring and without having to rely on batteries as a source of power. The technology is currently known as “broadband powerline” or “BPL,” or “powerline communication” or “PLC.” Within these categories, the technology discussed herein below is the subcategory of so-called “in-home” or “in-building” BPL or PLC. However, the apparatus necessary for interfacing consumer products with the AC power line has only been developed to a limited degree. What is needed are innovative designs for devices that obtain electrical power from the AC power line and utilize a low cost high speed data interface in a power line communications system for supplying signals required by such devices.
Prior art solutions to this problem typically utilize a standard AC plug inserted into a standard AC receptacle for interfacing a consumer device to the AC power line. This works for devices located near the floor (in the typical residence), devices connected to a line cord, or devices that have no limitation as to where access to the AC power line is provided. However, there is another class of devices that are not well-adapted to this particular line cord and plug/receptacle interface, that may be mounted in a ceiling or on a wall near the ceiling or in which a line cord is not supplied. Some examples of this class of devices include (a) entertainment devices such as loudspeakers; (b) comfort devices such as HVAC sensors and controls, air filtering and conditioning; (c) security apparatus such as motion and proximity sensors, sound sensors or cameras; (d) communication terminal equipment; and the like.
Besides the conventional wall outlet or receptacle for accessing the AC power line, the other standard connection mechanism for connecting a device to the AC power line is the light bulb socket. Light bulb sockets are available in a variety of types and sizes. The most common is the standard medium lamp receptacle used for installing incandescent light bulbs having the well-known threaded medium lamp base. The medium lamp base and receptacle provides two electrical contacts and is rated for device power requirements of up to 300 watts. The threaded portion of the base or receptacle (the “shell”), is connected to the neutral side of the AC line circuit and the center contact of the base or receptacle is connected to the line or “hot” side of the AC line circuit.
There are several advantages of a light bulb socket as compared to a wall outlet, including (a) no line cord or plug is required—the device is simply screwed into the socket; (b) the mechanical connection is via a threaded connector, not one that relies on spring tension in the contacts of the connector to maintain a tight, mechanically secure connection; and (c) a light bulb socket is likely to be located in a wider variety of places and is thus more versatile and adaptable to a variety of devices that require both AC power and a reliable high speed data access.
Loudspeakers are typical of the kind of device that ordinarily require wiring to convey the sound signals to them. In the case of so-called “powered speakers,” especially suitable for remote or extension speakers, AC power wiring is also usually required for their operation. Thus, the installation of extension speakers or ceiling speakers or surround sound speakers in an existing home environment requires that wiring for the AC power or for the audio signal or both be installed before the speakers may be used. Installation of such wiring is often a difficult and expensive task that typically requires the skills of an electrician to install the wiring properly, safely, and to accommodate local building codes. As a result, to avoid the cost and inconvenience, speakers may often be installed by non-electricians with haphazard wiring, often in unsightly fashion.
For example, several solutions exist in the prior art for coupling a powered loudspeaker system to the AC power line. This includes the traditional one of running the audio signal wires from the audio signal source through the wall or along the wall or baseboard to the extension speaker. In another example of a solution disclosed in U.S. Pat. No. 5,980,057 issued to Borchardt, et al., a speaker assembly adapted to be installed in a light bulb socket is equipped with an FM wireless receiver. The FM receiver receives broadcast signals over a modulated RF carrier in the 900 MHz band. The FM receiver demodulates the sound signal for play back via an amplifier coupled to the loudspeaker. However, the FM receiver must lock to a particular station or channel, it has a limited range because of the restrictions on devices operating in the 900 MHz band, and is susceptible to interference from broadcast FM stations operating in the same geographical area. This analog technology for conveying the audio signal is also susceptible to interference in the form of electrical noise and transients that are often present on the AC power line. By contrast, the digital modulation technologies are much more immune to interference that is largely comprised of such amplitude disturbances in the AC waveform. What is needed is a speaker unit that obtains the signals by a more robust and interference-free system than is available with analog FM modulation of an RF carrier, whether the medium is wireless broadcast or a power line carrier system.
In another example, disclosed in U.S. patent application No. US 2003/0197807 filed by Wu, a surveillance unit is mounted in a light socket and receives power from the light socket. Video data from a camera in the surveillance unit and/or audio data from a microphone may be sent via a wireless transceiver or via a power line network to a control or display location. The surveillance unit may include a speaker for playing audio information. However, the disclosed device is essentially a surveillance device which transmits information from its location via some undefined wireless or power line communication apparatus. There is little or no disclosure or teaching of transmitting or receiving and processing high speed data for use in data terminal devices connected to the AC power line via a lamp socket, the use of a lamp socket as a high speed data interface, or how the “audio information” is processed and communicated from a microphone or to a loudspeaker in a device connected to a lamp socket.
What is needed in this example of a loudspeaker system, or any other data receiving device, is a simple, inexpensive way to provide both AC power and robust, high speed data to the location of an extension or surround sound or ceiling speaker (or other data receiving device) without having to install new wiring. This would enable a person to simply install the speaker or other device in a suitable location just as he or she would install a light bulb. Such a system would also supply the audio or other signal to it via a power line communication system without having to run separate wiring to the installed speaker system or data terminal device. Besides being easy to install, the high speed data communications network on the power line that is used to convey the signal information (data) must be selected on the basis of robustness, resistance to the effects of interference, and able to maintain accepted standards for Quality of Service (QoS).